And, aged 85, he’s still passing on his invaluable wisdom.
“If you don’t know this bloke you don’t know anything about boxing,” says Robert Riley, a former professional fighter and owner of Riley’s Boxing & Fitness Centre in Grimesthorpe where Alwyn trains his latest protégé – 19-year-old Khalid Ayub.
As an amateur, Khalid boxed for England from the age of 12 and won four national titles as well as two British titles and no fewer than seven Yorkshire titles. He turned professional last year, signing with management company MTK Global.
The light heavyweight from Mytholmroyd, near Halifax, was introduced to Alwyn through his dad, Gee, who is originally from Pitsmoor.
"This guy knows more about boxing than I could ever dream of, he’s a very special man,” Gee says.
"He’s had more than 100 champions, he’s probably the most successful amateur trainer ever.”
Gee recalls first meeting Alwyn in the 1980s when he was using a camera to record and analyse his fighters, something which is common practice now but was almost unheard of back then.
"My dad’s always had admiration for him,” says Khalid.
Alwyn, from Chapeltown, began coaching when he left the army in 1958. He has since worked for both England Boxing and Team GB in roles such as world class performance coach, national schoolboy coach and female national coach.
As well as Adams and Froch, Anthony Crolla, David Haye and Amir Khan are among the decorated fighters he’s coached over the years – and he still works with former Olympian Natasha Jonas.
"Control the feet, control the fight” is his motto in the gym and during our time together he bounces around the room with more energy than someone less than half his age, giving out instructions to Khalid and others training.
So what makes a champion, in Alwyn’s opinion?
"You need skill but also it’s that dedication as well,” he tells The Star.
"No more so than Clinton Woods, when he was 17 no one thought he would win a British title let alone a world title.”
"A good chin and a willingness to learn,” he adds. “Never stop learning. I’m still learning now.”
A former boxer himself who would fight up to three times a day when it was allowed, Alwyn tells how the sport saved his life.
He was given less than half an hour to live in 1970 when he contracted sepsis, but miraculously survived.
"When I was coming out of hospital the consultant called me over and said ‘You don’t know how lucky you are’. He said I survived because of my remarkable physical health, and that was through boxing.
"Within a month I was back in the gym.”
The sport has also provided him with a release in recent weeks following the death of his wife of 64 years Maureen, who passed away with Alzheimer's aged 82.
"If it wasn’t for boxing I don’t know where I would be,” he says.
"When you go home it’s lifeless. Boxing gets me out five or six days a week and the boxers come to see me.”
Adams and fellow Olympic gold medalist Anthony Joshua are among those who have progressed on to bigger and better things but still keep in touch with Alwyn.
"I have worked with Anthony Joshua, I have known him a long time because he was big friends with Nicola,” he adds.
"My wife used to come along and he would always come across and give her a hug. He’s a very nice fellow.”
Attention turns back to Khalid, who is still being put through his paces and is now drenched in sweat – his grey t-shirt has turned a shade darker.
He began boxing at just three years old when Gee bought him a punch ball before taking up the sport “properly” aged eight, with his first fight coming two years later.
“We are not going to rush him because at his weight most of the champions are in their 30s,” says Gee, who dedicates himself full time to supporting Khalid and his younger brother Nile, 14, an aspiring footballer in Sheffield United’s academy.
"I reckon he can be a world champion. I really believe in him, it’s not just because he’s my son. I know if he really works hard he’s got a really good chance,” he adds.
"Alwyn has been around a lot of champions, he’s not one to say he’s very special if he’s not. If I thought he wasn’t good enough I would have told him not to turn professional.”
Taking a break from the punch bag, Khalid adds: “My dad’s always the one who believes in me, whatever he’s said I can achieve I have gone on to do it.
"People might look at it and say it’s arrogant, but I just believe I can and I know how hard I work in the gym.
"My hope for the next 12 months is to get my first fight and hopefully have two or three. I don’t want to say I want to be winning titles straight away because it’s not realistic.”
What does his experienced trainer think?
“He's a very good puncher and he’s got a right engine on him, he can go a long way.”
A world champion?
"I hope so, but in any sport you need that bit of luck as well.”
And some wisdom from the likes of Alwyn.